Everything You Need to Know about Narcissists, Psychopaths, and Abuse - click on this link: http://www.narcissistic-abuse.com/faq1.html
In 1835, the British J. C. Pritchard, working as senior Physician at the Bristol Infirmary (hospital), published a seminal work titled "Treatise on Insanity and Other Disorders of the Mind". He, in turn, suggested the neologism "moral insanity".
To quote him, moral insanity consisted of "a morbid perversion of the natural feelings, affections, inclinations, temper, habits, moral dispositions, and natural impulses without any remarkable disorder or defect of the intellect or knowing or reasoning faculties and in particular without any insane delusion or hallucination" (p. 6).
He then proceeded to elucidate the psychopathic (antisocial) personality in great detail.
Thus, "psychopathic personality" came to mean both "abnormal" and "antisocial". This confusion persists to this very day. Scholarly debate still rages between those, such as the Canadian Robert, Hare, who distinguish the psychopath from the patient with mere antisocial personality disorder and those (the orthodoxy) who wish to avoid ambiguity by using only the latter term.
Moreover, these nebulous constructs resulted in co-morbidity. Patients were frequently diagnosed with multiple and largely overlapping personality disorders, traits, and styles. As early as 1950, Schneider wrote:
"Any clinician would be greatly embarrassed if asked to classify into appropriate types the psychopaths (that is abnormal personalities) encountered in any one year."
Full text here: http://www.narcissistic-abuse.com/personalitydisorders9.html
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 3 DVDs with 16 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)